As is known in the art, GaN Heterojunction Electron Mobility Transistor (HEMT) devices are finding their way into many Radio Frequency (RF) amplifier and power electronics applications with standoff (drain supply) voltages in the range of tens of volts to hundreds of volts. In these applications it may be required to set the quiescent bias condition of the HEMT to one of several conditions; for example in amplification applications it might be necessary to switch between Class A, A/B, B and standby (off) biasing condition. Also it is necessary that the bias classification or quiescent current condition be achieved in the presence of HEMT process variations. Additionally in a multiple biasing scenario it is desirable that the voltage command signals used to set the biasing point of the high voltage HEMTs come from interface circuitry, such as low voltage CMOS circuitry. Typically these signals are 2.5 volts or less and the underlying circuitry is unable to tolerate the high supply voltages of the GaN HEMT.